Street lighting systems may comprise a plurality of ballast lamps or light-emitting diode (LED) based luminaires. Such street lighting systems can be controlled to be turned on and turned off in accordance with the length of night and day. Such control can be provided by a simple clock or can be provided by a sensor-based system which senses the amount of ambient light and effectively switches the lighting system ON and OFF when the ambient light falls below or exceeds a predetermined threshold value.
Whilst it is known that utility companies providing street lighting systems can determine their energy usage for entire systems to within 10% of the actual metered energy usage. This means that the value of the metered energy is not accurate, with large over- and under-estimations being made of the actual energy consumed. Moreover, the metered energy of individual elements, for example, for each luminaire, within the lighting system cannot be determined.